According to the U.S. Census Bureau, in 2009, 7.8% of Americans had a travel time to work of more than 60 minutes. An urban economist believes that the percentage of Americans who have a travel time to work of more than 60 minutes has increased since then. She randomly selects 80 working Americans and ﬁnds that 11 of them have a travel time to work that is more than 60 minutes. Test the urban economist’s belief at the α = 0.1 level of signiﬁcance.
Answer to relevant QuestionsOne of the more popular statistics reported in the media is the president’s job approval rating. The approval rating is reported as the proportion of Americans who approve of the job that the sitting president is doing and ...In the United States, historically, 40% of registered voters are Republican. Suppose you obtain a simple random sample of 320 registered voters and ﬁnd 142 registered Republicans. (a) Consider the hypotheses H0: p = 0.4 ...Suppose we are testing the hypothesis H0: p = 0.3 versus H1: p > 0.3 and we ﬁnd the P-value to be 0.23. Explain what this means. Would you reject the null hypothesis? Why? To test H0: µ = 80 versus H1: µ < 80, a simple random sample of size n = 22 is obtained from a population that is known to be normally distributed. (a) If x̄ = 76.9 and s = 8.5, compute the test statistic. (b) If the ...In a study published in the American Journal of Psychiatry (157:737–744, May 2000), researchers wanted to measure the effect of alcohol on the development of the hippocampal region in adolescents. The hippocampus is the ...
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